About Amanda De Oliveira Silva

I have served as an Assistant Professor and Small Grains Extension Specialist at Oklahoma State University since August 2019. I believe that close interaction with producers is vital to understand their production strategies and to establish realistic research goals. My program focuses on developing science-based information to improve the agronomic and economic viability of small grains production in Oklahoma and in the Southern Great Plains.

Oklahoma Wheat Harvest at Standstill after Early Start

Courtesy Oklahoma Wheat Commission

Oklahoma wheat harvest is at a standstill after an early season start in Southwest, Oklahoma.   Not much has changed since the last report since no wheat has been taken in. Rains have moved across the state in all regions the past two days.  Even though producers would like to get into fields in all regions, the rain has been welcomed because of the extreme drought conditions across Southwest, Western, Panhandle and Central Oklahoma regions.  Yields are ranging in the mid-teens to mid 20’s. We did have a report of one field making 41 bushels per acre by Chattanooga and we had one report of a field coming in at 38 bushels per acre by Frederick.  It has been noted in some places of South Central, Oklahoma producers are hopeful to have better yields on wheat that had more intensive management plans, however yields will still be extremely poor in most locations.   Proteins have been favorable ranging mostly from 11 to 13%, with a report of one load making 18.36%.  Test weights are ranging all over the board from 58 to 61 pounds/bushel. (It should be noted test weights at this point in time are holding up much better than anticipated with more 60 to 61 pound/bushel test weight wheat). Producers will still have to wait and see how the rains across the state this week will impact those numbers.  Several places in Southwest and far Western Panhandle regions received over an inch of moisture.  In parts of the Panhandle, it has been the first measurable rain over the past 180 days, and in these regions the dryland wheat will most likely not be harvested.

Grandfield-Harvest really started moving over the weekend around this location. 43 truckloads were taken in. Yields being reported in the 20-25 bushel per acre range.  Test weights ranged from 60-61 pounds/bushel.  Protein was ranging from 11 to 13%, with a large amount being reported in the 12 to 12.5% range.  Moisture ranged from 10 to 15%.

Tipton-Harvest in this region also began, yields have been ranging from the mid 15’s to mid 20’s.  Test weights ranging from 59 to 61 pounds/bushel.  Proteins ranging from 11 to 12.5% range. Moisture ranged from 11.5 to 14%.  It is predicted these beginning fields are the poorer quality wheat and producers are hopeful yields might improve slightly as they get into better wheat.

Walters- Harvest started moving good in this region over the weekend. Yields being reported in the mid 20’s, with some reports on some of the wheat with intensive management making 41 bushels per acre.  Test weights ranged from 58 to 62 pounds/bushel. Proteins ranging 11 to 14%.  One protein was reported at 18.36%

Frederick-Test weights ranging from 59 to 62 pounds/bushel.  Proteins ranging from 10 to 13.5% range. Yields being reported from low teens to one coming in at 38 bushels per acre.

Granite/Lone Wolf/Altus- Harvest just started in these regions over the weekend with a little of wheat being taken in these regions.  Test weights ranging from 57 to 58 pounds/bushel on the four loads being reported.  Proteins ranged from 11.2 to 13.1%  Yields reported in mid teens, with one being reported in the low 20’s, this is on early cutting, a more representative sample will come in the next report once harvest gets rolling more.

Below see actual rainfall accumulations for the past two days with comparisons to the 180 day rainfall accumulations across Oklahoma.  Also please see the 7 day forecast provided by the Oklahoma Mesonet. Due to the heavy moisture and cooler temperatures most think it will be the end of Memorial Day weekend or possibly the beginning of next week before producers start getting back into the fields in most locations. For this reason the OWC will not publish a harvest report on Memorial Day but will publish a fully detailed report on Wednesday, June 1, 2022.

Wheat Disease Update – 19 May 2022

This article was written by Meriem Aoun, Small Grains Pathologist

During my visit to wheat fields in Morris (Okmulgee County) on May 16, I observed multiple fungal and bacterial diseases. Wheat crop in Morris looked good and tall compared to other locations in Oklahoma (Figure 1). Morris got substantial amount of precipitation, which favored some fungal and bacterial diseases.

Figure 1. Winter wheat crop in Morris, Oklahoma was in good condition as of May 16, 2022 (Courtesy Dr. Amanda Silva).

Bacterial streak (on the leaf, Figure 2) and black chaff (on the head, Figure 3) were frequently observed on multiple winter wheat varieties including ‘Big country’ and ‘WB 4401’. Bacterial streak and black chaff are two phases of the same disease and are favored by humid and warm climate, which was the case in Morris.

Figure 2. Symptoms of bacterial streak on the winter wheat variety ‘WB 4401’ in Morris, Oklahoma (Courtesy Dr. Amanda Silva; May 16, 2022).
Figure 3. Symptoms of black chaff on glumes and neck (Morris, Oklahoma; May 16, 2022).

In Morris, I also observed Septoria leaf spot and tan spot in the lower and mid canopy, but nothing much on flag leaves. Septoria leaf spot was more common and found on varieties like ‘Skydance’ and ‘Crescent AX’ (Figure 4). Both diseases were also observed in the Stillwater Agronomy Research Station on OSU winter wheat breeding lines. In addition, spot blotch and powdery mildew were found in multiple experimental plots in Stillwater on susceptible winter wheat varieties and OSU breeding lines (Figure 5).

Figure 4. Septoria leaf spot symptoms on the winter wheat variety ‘Crescent AX’ in Morris, Oklahoma (May 16, 2022).
Figure 5. The black spots show symptoms of spot blotch whereas the white patches correspond to powdery mildew infection on an OSU winter wheat breeding line (Stillwater, Oklahoma; May 11, 2022).

Powdery mildew and leaf rust were observed in both Stillwater and Morris (Figure 6 and 7). As I previously reported powdery mildew was observed in multiple locations in Oklahoma since April whereas leaf rust was first observed this year in Oklahoma during the second week of May.

Figure 6. Leaf rust symptoms on the hard red winter wheat variety ‘Baker’s Ann’ (Morris, Oklahoma; May 16, 2022).
Figure 7. Symptoms of leaf rust (circular orange pustules) and powdery mildew (white patches) on the hard red winter wheat variety ‘Baker’s Ann’ (Morris, Oklahoma; May 16, 2022).

In addition to these foliar diseases, I observed some head diseases including sooty mold (black head mold) (Figure 8) in wheat fields in Morris, El Reno, and Stillwater. Humid conditions promote this disease on wheat heads. Often wheat that has been subjected to a stress such as freeze, root rot, or drought shows a greater severity of sooty mold than healthy wheat. I also observed loose smut (Figure 9) in Chickasha, Stillwater, and Morris.

Figure 8. Symptoms of sooty mold on winter wheat in Morris, Oklahoma (May 16, 2022).
Figure 9. Symptoms of loose smut on the winter wheat variety ‘WB 2158’ (May 3, 2022).

Wheat Disease Update – 12 May 2022

This article was written by Meriem Aoun, Small Grains Pathologist

Root/crown/foot rots were observed in multiple wheat fields in April and May in Woods, Cherokee, Blaine, Cotton, and Payne counties. Dr. Amanda Silva reported severely damaged wheat plants in drought stressed fields mainly in Cherokee and Woods counties (Figure 1). Infected plants were stunted and white and had poor root systems. Although the plants were drought stressed throughout the growing season, much of the damage was not noticeable until after wheat heading. Dr. Silva observed pinkish discoloration on infected plants in Cherokee after peeling the leaf sheath in the lower stem internodes, which indicates that the infection was caused by Fusarium (Figure 2).

Figure 1. White, stunted, and drought-stressed plants showing symptoms of root/crown/foot rots (Cherokee county, Oklahoma; photo credit: Dr. Amanda Silva; May 12, 2022).
Figure 2. Pink discoloration indicates that root/crown/foot rot was caused by Fusarium (Cherokee county, Oklahoma; photo credit: Dr. Amanda Silva; May 12, 2022).

The rain in early May in some locations in Oklahoma provided suitable environmental conditions for the appearance of some fungal diseases including rusts. This week, stripe rust was observed in the Stillwater Agronomy Research Station on susceptible wheat varieties like ‘Pete’ and some OSU breeding lines (Figure 3). Leaf rust was found on the susceptible wheat variety ‘OK Bullet” and on some OSU breeding lines (Figure 4). Rust diseases have not been found in other locations in Oklahoma. The current pressure is low and late compared to the previous year due to drought conditions through the growing season. However, rust disease incidence can increase in coming weeks if weather conditions are favorable.

Figure 3. Stripe rust on a susceptible OSU winter wheat breeding line in the Stillwater Agronomy Research Station, Oklahoma (the photo was taken on May 10, 2022).
Figure 4. Initial leaf rust pathogen infection on a winter wheat OSU breeding line in the Stillwater Agronomy Research Station, Oklahoma (the photo was taken on May 10, 2022).

Wheat Disease Update – 28 April 2022

This article was written by Meriem Aoun, Small Grains Pathologist

During April, the Plant Disease and Insect Diagnostic Laboratory at OSU received multiple wheat samples showing symptoms of streaking on the leaves. Leaf streaks were greenish yellow and parallel as shown in Figure 1. Enzyme linked immunosorbent assay (ELISA) on these samples from different wheat varieties were positive for wheat streak mosaic virus (WSM). WSM infected samples were from fields in multiple counties in Oklahoma including Payne, Blaine, Cimarron, Harper, Grady, and Garfield. A couple of samples that tested positive for WSM were also positive for high plains virus (HPV) and were from Harper and Blaine counties. Both WSM and HPV are transmitted by wheat curl mite. I also observed symptoms of barley yellow dwarf virus (Figure 2) in fields in Payne, Cleveland, and Grady counties.

Figure 1. Wheat streak mosaic virus symptoms on the wheat variety ‘OK Corral’ (Grady County, April 13, 2022).
Figure 2. Symptoms of barley yellow dwarf infection on the wheat variety ‘OK Corral’ in a farmer field in Cleveland County, OK (the photo was taken by Bradley Secraw, extension educator, at Cleveland County on April 26, 2022).

I also observed leaf spotting on the wheat variety ‘OK Bullet’ in the Stillwater Agronomy Research Station. Culturing from the leaves resulted in the identification of the fungi Bipolaris sorokinana which causes spot blotch and Parastagonospora nodorum which causes septoria nodorum blotch. Parastagonospora nodorum was also recovered from leaf spots on leaves of the variety OK Corral in Cleveland County.

Around mid-April, the OSU Diagnostic Lab received a wheat sample from the varietyDoublestop CL Plus’ from Blaine County. I examined the sample and I found that the infected plants were stunted and brown and showed weak root systems (Figure 3). Culturing from infected tissues identified Bipolaris sorokiniana which causes common root rot and Fusarium sp. which cause root, crown and foot rots. These fungi are favored by drought conditions in Oklahoma during the fall and spring. Dr. Silva and Gary Strickland also reported seeing root rot at Cotton county.

Figure 3. Common root rot and Fusarium root, crown and foot rots in a wheat sample from the wheat variety ‘Doublestop CL Plus’ (Blaine County, April 13, 2022).

Wheat Disease Update – 21 April 2022

This article was written by Meriem Aoun, Small Grains Pathologist

In my previous update on April 12, I reported barley yellow dwarf virus (BYD) infection on the susceptible wheat variety ‘Pete’ in the BYD nursery in the Stillwater Agronomy Research Station. Last week, Dr. Amanda De Oliveira Silva (OSU Extension small grains specialist) observed yellowing of the leaf tips in most of the hard red winter wheat variety demonstration plots in Stillwater (Figure 1). We performed Enzyme linked immunosorbent assay (ELISA) on symptomatic samples from different OSU wheat varieties including ‘OK Corral’, ‘Strad CL Plus’, ‘Guardian’, ‘Baker’s Ann’, ‘Showdown’, and ‘Breakthrough’. All samples were tested positive for BYD. In these demonstration plots, the variety ‘Uncharted’, which carries two BYD resistance genes, Bdv1 and Bdv2, was the most resistant OSU wheat variety to BYD (Figure 1). Dr. Silva indicated that the plots planted earlier in September were more infected than the plots planted later in October. This shows the importance of breaking the ‘green bridge’ to manage this virus which is transmitted by cereal aphids.

Figure 1. The photo on the left shows Barley yellow dwarf (BYD) infection on the wheat variety OK Corral. The photo on the right shows the BYD resistant variety Uncharted which was planted next to other infected plots. The photos were taken in the hard red winter wheat variety demonstration plots in Stillwater, OK on April, 15, 2022.

During the last couple of weeks, the Plant Disease and Insect Diagnostic Laboratory at OSU received wheat samples from Garfield, Blaine, Cleveland, and Harper counties in Oklahoma and from an unknown location in Kansas state. I examined these samples and I observed yellowing and streaking indicative of viral infection (Figure 2). I did not observe any symptoms of fungal diseases on the leaves of the received samples. For the samples received from Garfield county and Kansas state, many of the leaves were dry and brown suggesting freeze damage (Figure 3).

Some of these samples were tested using ELISA for several viruses that affect wheat in the Great Plains. The sample from Cleveland county which was collected on the wheat variety OK Corral was positive for BYD. The sample from Kansas state (from the variety ‘Zenda’) and the sample from Garfield county (from the variety ‘WB 4401’) were tested positive for wheat streak mosaic virus (WSM). ELISA for the remaining samples from Blaine and Harper counties is in progress but the symptoms suggest WSM infection.

Figure 2. Symptoms of wheat streak mosaic virus on the leaves of the wheat variety ‘WB 4401’ (Garfield county, Oklahoma on April 13, 2022).
Figure 3. Freeze damage on the wheat variety ‘WB 4401’ (Garfield county, Oklahoma, photo by Kevin Brown on April 11, 2022).

Wheat Disease Update – 12 April 2022

This article was written by Dr. Meriem Aoun, Small Grains Pathologist

During the first and second week of April, some wheat diseases appeared in Oklahoma. For example, in the Stillwater Agronomy Research Station, I observed high powdery mildew infection on the susceptible wheat variety ‘OK Bullet’ (Figure 1). Similarly, Bradley Secraw (Extension educator at Cleveland county; March, 31, 2022) found little powdery mildew infection on the variety ‘OK Corral’ which is moderately resistant to this disease. In Stillwater and on April 11th, I observed initial stripe rust infection on OK Bullet (Figure 2). Also recall in my previous update of 25-March, I indicated seeing little stripe rust infection in Jackson county. Therefore, I encourage growers to start scouting their fields for these diseases, especially if they are growing susceptible varieties. We will continue to monitor these diseases as we approach flag leaf stage and provide recommendations.

Figure 1. Powdery mildew infection on the susceptible wheat variety ‘OK Bullet’ in Stillwater, OK (April, 11, 2022)

In the Stillwater Agronomy Research Station, I also observed barley yellow dwarf virus (BYD) symptoms on the susceptible wheat variety ‘Pete’. The symptoms appeared as yellow, red/purple discoloration on the leaves as shown in Figure 2. This virus is transmitted from plant to plant by cereal aphids. Enzyme linked immunosorbent assay (ELISA) on a symptomatic sample from Pete was positive for two BYD strains; BYD strain 2 (BYDV-PAV) and cereal yellow dwarf (CYDV-RPV).

Figure 2. Barley yellow dwarf virus symptoms on the susceptible variety ‘Pete’ in Stillwater, OK (April, 5, 2022).

In Stillwater, I observed yellowing on the wheat variety ‘Lonerider’. Older leaves were completely chlorotic (Figure 3). Laboratory diagnosis of a sample using ELISA was positive for wheat streak mosaic virus (WSM) which is transmitted by wheat curl mite. This disease is an issue in our region as many wheat varieties growing in Oklahoma are susceptible to WSM.

Figure 3. Symptoms of wheat streak mosaic virus on the susceptible wheat variety ‘Lonerider’ in Stillwater, OK (April, 5, 2022).

Wheat Disease Update – 25 March 2022

This article was written by Meriem Aoun, Small Grains Pathologist

Based on my observations in Stillwater wheat fields and communications with multiple county educators in Oklahoma, it is relatively quiet in terms of diseases. In southwestern Texas and during the first week of March, Dr. Amir Ibrahim (Regents Professor & Small Grains Breeder/Geneticist; Texas A&M AgriLife Research) and Dr. Bryan Simoneaux (Research Associate, Texas A&M AgriLife Research) reported infections of stripe rust and leaf rust in naturally infected rust nurseries.

In Castroville, TX (29.3558° N, 98.8786° W) nursery, Drs. Ibrahim and Simoneaux observed a little bit of leaf rust in the lower canopy of the hard red winter wheat variety ‘Jagalene’. In the Uvalde, TX (29.2097° N, 99.7862° W) nursery, they observed some leaf rust on the lower canopy of the hard red winter wheat varieties Jagalene and ‘TAM 110’, however leaf rust infection did not spread uniformly throughout the nursery. They also found good stripe rust infection on Jagalene in Uvalde, TX (Figure 1 & 2).

Figure 1. Leaf rust and stripe rust infections on the same leaf of the susceptible wheat variety Jagalene at Uvalde, TX (Photo by Dr. Bryan Simoneaux on 3 March 2022).
Figure 2. Stripe rust infections on the susceptible wheat variety Jagalene at Uvalde, TX (Photo by Dr. Bryan Simoneaux, on 3 March 2022).

In southwestern Oklahoma and during the first week of March, Gary Strickland (Jackson County Extn Educator) reported seeing only very little tan spot on bottom leaves but nothing major (in terms of percentage infestation). He also noted a few leaves infected with stripe rust. Gary Strickland mentioned that the major issue he observed was winter grain mites.

In the Stillwater Agronomy Research Station and on 24 March 2022, I am starting to observe symptoms of the wheat soil-borne mosaic (SB)/wheat spindle streak mosaic (SS) virus complex on the susceptible hard red winter wheat variety ‘Vona’ in the SB-SS nursery (Figure 3). However, due to the use of resistant varieties, these viral diseases are not a problem in Oklahoma and the central plains.

Figure 3. Symptoms of wheat soil-borne mosaic/wheat spindle streak mosaic virus complex on the susceptible wheat variety Vona in Stillwater, OK

First Hollow Stem Update – 3/22/2022

Amanda de Oliveira Silva, Small Grains Extension Specialist

First hollow stem (FHS) is the optimal time to remove cattle from wheat pasture. This occurs when there is 1.5 cm (5/8”, or the diameter of a dime) of hollow stem below the developing grain head (see full explanation). The latest FHS results from OSU forage trials in Stillwater (Table 1) and Chickasha (Table 2) are listed below. For an additional resource, see the Mesonet First Hollow Stem Advisor.

We use an accelerated growth system to report the earliest onset of FHS stage. Trials are seeded early to simulate a grazed system, but the forage is not removed. Varieties reported here with the earliest FHS date should be the first to monitor in commercial fields. In practice, wheat that is grazed will likely reach FHS stage later than reported here, and differences between varieties will likely moderate.

Values can fluctuate from one sampling to another due to environmental variation associated with, among other factors, the winter storm on February 2-4. Additionally, varieties differed widely in their FHS response following this cold period.

Table 1. First hollow stem (FHS) results for each variety collected at Stillwater. Plots were planted on 09/27/21 but not grazed or clipped. The threshold target for FHS is 1.5 cm (5/8″ or the diameter of a dime). The value of hollow stem for each variety represents the average of ten measurements. Varieties exceeding the threshold are highlighted in red. The overall average represents the mean FHS for the varieties measured within a date.

Table 2. First hollow stem (FHS) results for each variety collected at Chickasha. Plots were planted on 09/28/21 but not grazed or clipped. The threshold target for FHS is 1.5 cm (5/8″ or the diameter of a dime). The value of hollow stem for each variety represents the average of ten measurements. Varieties exceeding the threshold are highlighted in red. The overall average represents the mean FHS for the varieties measured within a date.

Additional resources available:

Acknowledgements

Tyler Lynch, Senior Agriculturalist

Israel Molina Cyrineu, Graduate Research Assistant

Cassidy Stowers, Undergraduate student

Ephraim Muyombo, Undergraduate student

Lettie Crabtree, Undergraduate student

Teresa Swantek, Undergraduate student

First Hollow Stem Update – 3/18/2022

Amanda de Oliveira Silva, Small Grains Extension Specialist

First hollow stem (FHS) is the optimal time to remove cattle from wheat pasture. This occurs when there is 1.5 cm (5/8”, or the diameter of a dime) of hollow stem below the developing grain head (see full explanation). The latest FHS results from OSU forage trials in Stillwater (Table 1) and Chickasha (Table 2) are listed below. For an additional resource, see the Mesonet First Hollow Stem Advisor.

We use an accelerated growth system to report the earliest onset of FHS stage. Trials are seeded early to simulate a grazed system, but the forage is not removed. Varieties reported here with the earliest FHS date should be the first to monitor in commercial fields. In practice, wheat that is grazed will likely reach FHS stage later than reported here, and differences between varieties will likely moderate.

Values can fluctuate from one sampling to another due to environmental variation associated with, among other factors, the winter storm on February 2-4. Additionally, varieties differed widely in their FHS response following this cold period.

Table 1. First hollow stem (FHS) results for each variety collected at Stillwater. Plots were planted on 09/27/21 but not grazed or clipped. The threshold target for FHS is 1.5 cm (5/8″ or the diameter of a dime). The value of hollow stem for each variety represents the average of ten measurements. Varieties exceeding the threshold are highlighted in red. The overall average represents the mean FHS for the varieties measured within a date.

Table 2. First hollow stem (FHS) results for each variety collected at Chickasha. Plots were planted on 09/28/21 but not grazed or clipped. The threshold target for FHS is 1.5 cm (5/8″ or the diameter of a dime). The value of hollow stem for each variety represents the average of ten measurements. Varieties exceeding the threshold are highlighted in red. The overall average represents the mean FHS for the varieties measured within a date.

Additional resources available:

Acknowledgements

Tyler Lynch, Senior Agriculturalist

Israel Molina Cyrineu, Graduate Research Assistant

Cassidy Stowers, Undergraduate student

Ephraim Muyombo, Undergraduate student

Lettie Crabtree, Undergraduate student

Teresa Swantek, Undergraduate student

First Hollow Stem Update – 3/15/2022

Amanda de Oliveira Silva, Small Grains Extension Specialist

First hollow stem (FHS) is the optimal time to remove cattle from wheat pasture. This occurs when there is 1.5 cm (5/8”, or the diameter of a dime) of hollow stem below the developing grain head (see full explanation). The latest FHS results from OSU forage trials in Stillwater (Table 1) and Chickasha (Table 2) are listed below. For an additional resource, see the Mesonet First Hollow Stem Advisor.

We use an accelerated growth system to report the earliest onset of FHS stage. Trials are seeded early to simulate a grazed system, but the forage is not removed. Varieties reported here with the earliest FHS date should be the first to monitor in commercial fields. In practice, wheat that is grazed will likely reach FHS stage later than reported here, and differences between varieties will likely moderate.

Values can fluctuate from one sampling to another due to environmental variation associated with, among other factors, the winter storm on February 2-4. Additionally, varieties differed widely in their FHS response following this cold period.

Table 1. First hollow stem (FHS) results for each variety collected at Stillwater. Plots were planted on 09/27/21 but not grazed or clipped. The threshold target for FHS is 1.5 cm (5/8″ or the diameter of a dime). The value of hollow stem for each variety represents the average of ten measurements. Varieties exceeding the threshold are highlighted in red. The overall average represents the mean FHS for the varieties measured within a date.

Table 2. First hollow stem (FHS) results for each variety collected at Chickasha. Plots were planted on 09/28/21 but not grazed or clipped. The threshold target for FHS is 1.5 cm (5/8″ or the diameter of a dime). The value of hollow stem for each variety represents the average of ten measurements. Varieties exceeding the threshold are highlighted in red. The overall average represents the mean FHS for the varieties measured within a date.

Additional resources available:

Acknowledgements:

Tyler Lynch, Senior Agriculturalist

Israel Molina Cyrineu, Graduate Research Assistant

Cassidy Stowers, Undergraduate student

Ephraim Muyombo, Undergraduate student

Lettie Crabtree, Undergraduate student

Teresa Swantek, Undergraduate student